There is a balance between oxidative stress, antioxidant capacity and immune response. Their roles in physiological and behavioural mechanisms are important for the maintenance of the organism’s internal equilibrium. This study aimed to evaluate the antioxidant effects of the exogenous alga Spirulina platensis (Arthrospira platensis) in a stress-induced rat model, and to describe its possible mechanism of action. Thirty-six adult male Sprague Dawley rats were separated into four groups: control (C), stress (S), S. platensis (Sp), and S. platensis + stress (SpS). The rats in groups Sp and SpS were fed with 1,500 mg/kg b.w./day Spirulina platensis for 28 days. All rats were exposed to prolonged light phase conditions (18 h light : 6 h dark) for 14 days. The SpS and S groups were exposed to stress by being kept isolated and in a crowded environment. Blood samples were obtained by puncturing the heart on the 28th day. The effect of stress on serum corticosterone, oxidative stress markers (TOS, TAC, PON1, OSI) and immunological parameters (IL-2, IL-4, IFN-ɣ) were tested. Also, the brain, heart, intestines (duodenum, ileum, and colon), kidney, liver, spleen, and stomach of the rats were weighed. Serum corticosterone levels were higher in the S group than in the C group, and significantly lower in the SpS group than in the S group. Mean total antioxidant capacity were lower in the S group than in the C group, and Spirulina reversed this change. Although not significantly different, IL-2 was lower in the S group than in the C group. However, in the SpS group, IL-2 increased due to Spirulina platensis mitigating effects of stress. Male rats fed a diet with Spirulina platensis could experience significantly milder physiological changes during stress, although stress patterns may be different. Exogenous antioxidant supplements merit further investigation in animals and humans where the endogenous defence mechanism against stress may not be sufficient.

This study was conducted with the purpose of investigating the distribution of the Activating Transcription Factor 6 (ATF6) and the Nerve Growth Factor (NGF) in the duodenum tissue of diabetic and non-diabetic rats. Eighteen female Sprague dawley rats were randomly divided into three groups as thecontrol, sham and diabetes groups. Routine histological and immunohistochemical methods were appliedon the duodenum tissues collected at the end of the study.Results: It was determined that the villus length measurements showed a statistically significant differencebetween the control and diabetes groups. There was NGF immunoreactivity which was moderate anddiffuse cytoplasmic in the villus intestinalis and muscularis layer in all groups, weak in the crypts andglands in the control and sham groups and moderate and diffuse cytoplasmic in the diabetes group. ATF6immunoreactivity was determined moderate in the villus intestinalis, crypts, glands and muscularis layerin the control and sham groups and strong diffuse cytoplasmic in the diabetes group. It wasdetermined that both NGF and ATF6 immunoreactivity increased in the duodenum tissue of the rats onwhich diabetes was induced experimentally.